1. Field of the Invention
The present invention relates to an inhibitory agent suitable for kneaded meat, especially frozen fish surimi; a drip-inhibitory agent; an inhibitory agent for spongy-meat-formation induced by freezing; an agent for enhancing the stability formation of fish surimi; kneaded meat and process thereof; food products, including kneaded meat of poultry and animals, free of phosphate and with suppressed freezing-denaturation; a method for freezer storage for kneaded meat; a process for producing fish and meat paste products, especially, kamabokos, fish sausages, and kneaded meat of poultry and animals; a method for enhancing the formation of stability of kneaded meat; and a method for increasing the yield of kneaded meat.
2. Description of the Prior Art
In the field of recent food industry, it may tend to reduce or even avoid the use of food additives. Consumers' minds or feelings and social environment make food processors to explore food products, which are suitable for such commercial needs, and to reduce food additives as much as possible. Particularly, phosphates such as sodium pyrophosphate and sodium polyphosphate are used in fish and meat paste products to improve their freezing tolerance and moisture-retaining ability. However, excessive amount of intake of them may result in an unsatisfactory inhibition of absorbing calcium and minerals by the body, and may susceptibly induce diseases such as osteoporosis, growth inhibition, and taste-blindness. Because of this, the above tendency to avoid or even stop the use of phosphates is on going, particularly, movement or campaign to eliminate phosphates from fish paste products has been strikingly highlighted.
There exists a quite hard problem to be overcome in producing fish meat products without using phosphates while keeping the satisfactory processibility. Conventional frozen-surimi (frozen minced fish meat) free of phosphate, can be processed with only sugar, i.e., sucrose, in an amount of 5% by weight to frozen surimi available at stores and of 8% by weight to those which are processed and stored on ships. In these products, sugar only exerts a relatively-lesser inhibitory activity for freezing-induced protein-denaturation, and fails to keep their high-quality for a relatively-long period of time. Therefore, raw surimi should be used in some fields even though it is partial. In other words, raw surimi should be used without intention even if it is more quickly deteriorated than frozen surimi, meaning that it could not be diluted or brought up volume with water, it has no economical benefit and has only 3- to 4-days of shelf-life even under cold-storage conditions.
In conventional frozen-surimi in general, the protein denaturation thereof has been tried to be inhibited using 5% by weight of sucrose and 0.2% by weight of phosphate(s). Fish meat proteins are susceptible to denaturation when frozen and to lose their solubility against salts. The mechanism of the denaturation has not yet been solved, but the main causative is deemed to be the influence of calcium and magnesium on proteins, resulting in a use of phosphates which inhibit the denaturation of proteins.
It is understood that sugar fines down ice crystals, which are formed by freezing water in myofibrils of fish meat, and prevents the dehydration of proteins. Fish meat myosins in rod-shape molecules associate each other by forming intermolecular cross-links during cold storage, and coagulate by forming floc when the rod-shape molecules proceed to associate. Freezing denaturation is deemed to be triggered by the change of state of water. Proteins and other components in living tissues generally exist in a state where they are sufficiently saturated with water in such a manner that the molecular surfaces are covered with water. As a result, the higher-order structure of proteins is stabilized. It is understood that intramolecular bonds of hydrogen- and hydrophobic-bonds in proteins inevitably correlate to hydration state. Freezing of food products causes the icing and transfer of water, resulting in a removal of water around protein molecules and of hydration water partially or substantially wholly, and leading to an estimation of that the molecules are highly-dehydrated by some degree to loosen and cut the intermolecular cross-links and to confuse the higher-order structure of proteins. Thus, the effect of sugar is considered as follows: It physically causes ice-point reduction, fines down ice crystals, and prevents protein damage.
Stabilization of the quality of surimi free of phosphate, i.e., the prevention or inhibition of protein denaturation during cooling and freezing is quite impossible with only sugar because proteins are susceptible to denaturation during freezer storage, and then gelatinized and sponged to lose moisture-retaining ability by a large margin.
Under these circumstances, Japanese Patent Kokoku No. 23,385/72 discloses a conventional inhibitory agent for protein denaturation and a process for producing frozen-surimi; a technique for inhibiting the freezing denaturation of surimi by adjusting the pH of surimi before freezing to pHs of 7.5 to 9, and freezing the resulting surimi. Japanese Patent Kokai Nos. 135,927/95 and 9,931/96 disclose another techniques for inhibiting the freezing denaturation of fish surimi by adding trehalose.
Suisan-Kako-Shin-Genryo-Kaihatsu-Jigyo-Hokokusho (Annual Report of 1997 by the Project of Development for New Fishery Processing Materials) in 1997, published on July in 1998 by the Fishery Processing Division of Fishery Administration Department of Fishery Agency of Japan discloses a technique comprising mincing “tokage-eso”, i.e., Saurida elongate, and Atlantic cutlassfish, leaching the mixture in an alkaline electrolytic water with a pH of 10 to 11, dehydrating the mixture, adding sucrose and trehalose to the dehydrated mixture, and freezing the resulting mixture into a frozen surimi with improved gel-forming ability.
In conventional techniques using either trehalose or alkaline electrolytic water for leaching fish meat, there found insufficient inhibitory effect on freezing denaturation; the product yield reduction by dripping, spongy meat formation by freezing, and formation reduction of setting of fish surimi. Thus, development of higher technology will be highly appreciated.
In the prior art disclosed in the above Suisan-Kako-Shin-Genryo-Kaihatsu-Jigyo-Hokokusho (Annual Report of 1997 by the Project of Development for New Fishery Processing Materials), alkaline leaching reduces the product yield, and electrolytic water used for the leaching results in a problem of wastewater treatment. In general, kamaboko prepared with surimi containing a residual alkali may be incorporated into products, resulting in fragile mouth feel; Alkali-removing step should be required after alkaline leaching to avoid leached surimi from becoming to show alkaline pHs carefully.